Power control in battery-powered mobile devices is of increased concern in recent times. Most battery-powered mobile devices use a voltage regulator that can both limit and regulate power that is being supplied to the various electronic circuits in the device. Examples of battery-powered mobile devices include personal data assistants (PDAs), cellular telephones, portable messaging devices for email and text messages, digital cameras, personal music player devices, and others.
Various circuit arrangements have also been made for charging the battery and otherwise powering the portable device. For example, a coil in the battery-powered mobile device can be used to inductively generate a sinusoidal signal that is then rectified by a full-wave rectifier to generate a direct current (DC) voltage. The DC voltage is then filtered and regulated, for example, by a low dropout (LDO) voltage regulator to produce a regulated 5 volt source for powering the electronic circuits in the device.
Conventional full-wave bridge rectifiers utilize junction diodes. Each junction diode has a forward bias voltage drop of approximately 0.7V. Thus, for a full-wave bridge rectifier, the resulting voltage drop relative to the input voltage can be as high as 1.4 volts. A voltage drop of 450 millivolts can also be present across the LDO voltage regulator. Both of these voltage drops can generate an amount of heat that is often undesired.